in britain, they're celebratatg the second royal wedding of the year. this time, will and kate try not to steal the spotlight. but remember all those hats? they're back. >>> and check out this big thank you. an amazing moment off the coast. how a humpback whale, whose life was saved by a group of researchers, repaid the favor. >>> good evening. i'm dan harris. david muir is on assignment tonight in africa. we'll go to him in just a moment. but we want to start in washington, where tonight, we're seeing something highly unusual. hope. there was a real change of tone today in the debt debate. now, we should say, the hope now, we should say, the hope we're seeing tonight is still very tentative and very fragile. but with the clock ticking down, and there it is, three days left. some of the major players in this game are starting to sound like they might finally be getting down to business to break the impasse. abc's senior political correspondent, jon karl, has been on this story every step of the way. and he leads us off, once again, tonight. jon, good ev